1. Field of the Invention
The invention relates to a buck-boost converter, and more particularly to a buck-boost power factor correction (PFC) converter.
2. Description of the Related Art
The PFC (power factor correction) power converter is utilized to improve the power factor of AC power. The detail skill of the PFC converter can be found in prior arts, such as U.S. Pat. No. 7,116,090 “Switching control circuit for discontinuous mode PFC converters”. The traditional PFC approach is to convert the AC input to a DC voltage that is higher than the peak value of the line voltage. However, it might cause problem when a high line voltage is inputted, such as 380 VAC, etc. The most popular power electronic devices and motors are designed for 240 VAC input. The object of the present invention is to develop a buck-boost PFC converter to solve this problem. The output voltage of this PFC converter can be lower or higher than the line voltage.